Roles of carbohydrate reserves for local adaptation to low temperatures in the freeze tolerant oligochaete Enchytraeus albidus

• Published in: Journal of Comparative Physiology B
• Main Authors: Fisker, Karina Vincents, Overgaard, Johannes, Sørensen, Jesper Givskov, Slotsbo, Stine, Holmstrup, Martin
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: Bergen; Greenland; Kullen; Norway; Nuuk; Svalbard; Iceland
• Online Access: https://pure.au.dk/portal/en/publications/88fb2ade-b018-424d-87cd-245e02a1d593; https://doi.org/10.1007/s00360-013-0788-6

Geographic variation in cold tolerance and associated physiological adaptations were investigated in the freeze tolerant enchytraeid Enchytraeus albidus (Oligochaeta). Specimens from Svalbard, Greenland (Nuuk), Iceland (Hólar and Mossfellsbær) and continental Europe [Norway (Bergen), Sweden (Kullen) and Germany] were reared in the laboratory in a common-garden experiment. The aim was to test for variations in minimum lethal temperature, freeze duration tolerance, carbohydrate reserves and metabolic rate among the populations. Cold tolerance was related to environmental temperature of the respective location. Populations from the coldest climatic regions were able to tolerate freezing down to at least -15 °C and endured being frozen at -5 °C for 27-48 days, respectively. Populations from milder climates had a lower freeze duration tolerance (about -9 °C) and endured -5 °C for a shorter period (between 9 and 16 days). Glucose accumulation and glycogen reserves varied significantly between populations, but was not related directly to cold tolerance. Metabolic rate varied significantly between populations, but was not significantly related to cold tolerance. The metabolic rates at -2 °C of frozen and unfrozen worms from Germany and Svalbard were tested. The metabolic depression due to freezing of these populations was relatively small (